The term 'intersex' is actually, a fairly new term that is associated with the disorder.

Previously, this particular gender disorder has been reffered to as hermaphrodite, pseudohermaphrodite, and transgender.

Hermaphrodite is defined as "an individual in which reproductive organs of both sexes are present," and can be used in reference to organisms that are asexual such as plants and invertebrates.

Pseudohermaphrodite is defined as "an individual having internal reproductive organs of one sex and external sexual characteristics resembling those of the other sex or being ambiguous in nature."

Transgender is defined as "a person appearing or attempting to be a member of the opposite sex, as a transsexual or habitual cross-dresser."

Before you can fully understand the cause of intersex, one must understand the development of sexual differentiation, in which a productive human female has XX chromosome pair and a productive male has an XY pair of chromosomes.

During fertilization, the sperm will add either an X (female) or Y (male)chromosome to the X chromosome in thie ovum (egg cell), which is what determines the genetic sex of the embryo.

During the first weeks of development, genetic male and female fetuses are "anatomically indistinguishable," with primitive gonads beginning to develop during approximately the sixth week of gestation. The gonads, in a "bipotential state," may develop into either testes or ovaries depending on the chromosomes. Through the seventh week, male and female fetuses appear identical.

At around eight weeks of gestation, the gonads of an XY embryo differentiate into functional testes, secreting testosterone. Ovarian differentiation, for XX embryos, does not occur until approximately Week 12 of gestation. In normal female differentiation the müllerian duct system develops into the uterus, Fallopian tubes, and inner third of the vagina. In males the müllerian duct-inhibiting hormone MIH causes this duct system to regress.

By birth, the typical fetus has been completely "sexed" male or female, the hormones and genital development remaining consistent with the genetic sex.

So, that being said...

The final body appearance doesn't always correspond with what is dictated by the genes. In other words, there is sometimes an incongruence between genotypic (chromosomal) and phenotypic sex. Although there neither no less common chromosomal sex nor mosaicism/chimerism, but just the most common types (XY or XX), less common phenotypes still appear in such cases. In this sense, the common habit in the 21st century of elevating the role of the sex chromosomes above all other factors when determining gender may be analogous to the older habit of finding "true" sex in the gonads.

This phenomenon complicates the common XY sex-determination system, because it proves that genes don't always definitely determine the sex.

Middlesex:
A Novel
(Oprah's Book Club)

A story of a young girl, Callie, who is intersexual. Although, raised as a girl, genetically, physically, and mentally, she is male. Follow genome that transformed Callie into Cal.

Eugenides weaves together a kaleidoscopic narrative spanning 80 years of a stained family history, from a fateful incestuous union in a small town in early 1920s Asia Minor to Prohibition-era Detroit; from the early days of Ford Motors to the heated 1967 race riots; from the tony suburbs of Grosse Pointe and a confusing, aching adolescent love story to modern-day Berlin. Eugenides's command of the narrative is astonishing. He balances Cal/Callie's shifting voices convincingly, spinning this strange and often unsettling story with intelligence, insight, and generous amounts of humor.

"It's difficult to imagine any serious male writer of earlier eras so effortlessly transcending the stereotypes of gender. This is one determinedly literary novel that should also appeal to a large, general audience." -Publisher's Weekly

Ambiguous Genitalia:
Ambiguous genitalia can appear as either a large clitoris or small penis. Because there is variation in all of the processes of the development of the sex organs, a child can be born with a sexual anatomy that is typically female, or feminine, in appearance with a larger than average clitoris (clitoral hypertrophy). Or, typically male, masculine, in appearance with a smaller than average penis that is open along the underside. The appearance may be quite ambiguous, describable as female genitals with a very large clitoris and partially fused labia, or as male genitals with a very small penis, completely open along the midline ("hypospadic"), and an empty scrotum.

"True hermaphroditism"
With some conditions of intersex, even the chromosomal sex may not be clear. A "true hermaphrodite" is defined as someone with both male and female gonadal tissues (testes and ovarian tissue).

Ovotestes
Although there are no definite reports on any true hermaphroditism in humans, there is, on the other hand, a spectrum of forms of ovotestes. The varieties range, including having two ovotestes or having one ovary and one ovotestis. This is often in the form of streak gonads. Phenotype is not determinable from the ovotestes; in some case the appearance is "fairly typically female," in others it is "fairly typically male," and it may also be "fairly in-between in terms of genital development."

1. Treatments: Restore functionality (or potential functionality)
2. Enhancements: Give the ability to identify with "mainstream" people (for example: breast enlargement surgery)

But, there are other systems of management, which can fall into neither category.

In any case, the most common procedure is surgery.

Surgery
The exact procedure of the surgery depends on what is the cause of a less common body phenotype in the first place.

If
There is often concern whether surgery should be performed at all.

Traditional approaches to management of intersexuality has been socially motivated surgery. However, some say that surgical treatment is socially motivated and hence ethically questionable; without evidence doctors regularly assume that intersexed persons can not have a clear identity. This is often taken further with parents of intersexed babies advised that without surgery their child will be stigmatized.

In 20-30% of surgical cases to "treat" intersexed babies the result is loss of sexual sensation. Given these statistics and the fact that surgery is irreversible it is important to remember this is a material change based on a social framework.

When to preform surgery:
Most modern intersexed advocates argue surgery on intersexed babies should wait until the child can make an informed decision.

Congenital adrenal hyperplasia- (XX) The most common cause of sexual ambiguity is congenital adrenal hyperplasia (CAH), an endocrine disorder in which the adrenal glands produce abnormally high levels of virilizing hormones. In genetic females, this leads to an appearance that may be slightly masculinized (large clitoris) to quite masculine.

Progestin-induced virilisation- (XX) In this case, the male hormones are caused by use of progestin, a drug that was used in the 1950s and 1960s in order to prevent miscarriage. These individuals normally have internal and external female anatomy, with functional ovaries and will therefore have menstruation. They develop, however, some male secondary characteristics and they frequently have unusually large clitorises. In very advanced cases, such children have initially been identified as boys.

Androgen insensitivity syndrome- (XY) People with AIS have typically male chromosomes (XY), along with typically female appearance and genitalia.
Although people with AIS have a vagina, they lack a uterus, cervix of the uterus, and ovaries, and are thereby infertile. The vagina may be shorter than average; in some cases it is nearly absent. Instead of female internal reproductive organs, a person with AIS has undescended or partially descended testes, of which the person may not even be aware.

AIS may be called the genetic male's equivalent of CAH, since AIS affects people with XY genotype, while CAH affects people with XX genotype.

In complete androgen insensitivity syndrome ("CAIS"), the body reads no "male" hormones. In partial androgen insensitivity syndrome (PAIS), however, the body reads some androgens, so virilization occurs to a certain degree. PAIS results in genitalia that may be ambiguous, due to some, although limited, metabolization of the hormones produced by the testes. Ambiguous genitalia most frequently appear as a large clitoris, known as clitoromegaly, or a small penis, which is called as micropenis or microphallus.

5-alpha-reductase deficiency- (XY) In this condition, individuals have testes, as well as vagina and labia, but with a small penis capable of ejaculation instead of a clitoris (this penis, however, appears to be a clitoris at birth). These individuals are normally raised as girls. However, come puberty, their testes will descend, their voice will deepen and they often will develop a male sexual identity. People with this deficiency develop only limited facial hair.

Persistent müllerian duct syndrome- (XY) The child has XY chromosomes typical of a male. The child has a male body and an internal uterus and fallopian tubes because his body did not produce Müllerian inhibiting factor during fetal development.

Kallmann syndrome- (XY) This is a specific type of hypogonadotropic hypogonadism (HH) in which the distinguishing symptom is anosmia or hyposmia in addition to the HH symptoms of low levels of pituitary hormones LH and FSH. Kallmann Syndrome is not an intersex condition but does cause pubertal delay in both males and females. Some individuals with Kallmann's may regard themselves as intersex. However, this is possibly because they have other conditions such as PAIS in addition to Kallmann's. Such synchronous conditions is only present in a minority of people with Kallmann's, who mostly have no genital abnormality at birth. Therefore, mostly, there is no inconsistency of sex chromosomes with phenotype and they are therefore not intersex. Having pubertal delay but otherwise usual male or female body and fertility is not intersex.

Less usual chromosomal sex- addition to the most common XX and XY chromosomal sexes, there are quite a few other possible combinations such as Turner syndrome (XO), Triple X syndrome (XXX), Klinefelter syndrome (XXY), XYY syndrome (XYY), XX male, Swyer syndrome (XY female), and there are many other individuals who do not follow the typical patterns (such as individuals with four or even more sex chromosomes).

Mosaicism and chimerism- A mix can occur, where some of the cells of the body have the common XX or XY, while some have one of the less usual chromosomal contents above. Such a mixture is caused by either mosaicism or chimerism. In mosaicism, the mixture is caused by a mutation in one of the cells of the embryo after fertilization, while chimerism is a fusion of two embryos. Alternatively, it is simply is a mixture between XX and XY, and doesn't have to involve any less common genotypes in individual cells. This, too, can occur both as a chimerism, or that one sex chromosome has mutated into the other. On the other hand, however, not all cases of mosaicism and chimerism involve intersex.

Celebrities are always telling us that fame has its downsides, gossip being one of them. And, in this case, the actress Jamie Lee Curtis, who for two decades has been saddled with rumors that she was a hermaphrodite, intersexed, at birth.

These stories have never been proven, but most folks seem satisfied with the argument that it was passed along by a friend of a friend who knows a doctor who was told about it in medical school, or some variation thereof. If that doesn't convince the person, then it'll probably be pointed out that she adopted her two children instead of conceiving them.

On top of that, because she has a dual-gendered first name, it must prove she intersex. But, of course, this proves nothing.